C. Ober et al. in Polymer Journal, Vol. 14, No. 1, pp. 9-17 (1982) disclose liquid crystal polymers comprising aromatic ester mesogenic units containing flexible alkylene (or "polymethylene") spacers. For example, one type contains an aromatic ester triad with three linearly-aligned aromatic rings, the bis(p-carboxyphenyl) terephthalate moiety, and a polymethylene flexible spacer which can contain 2 to 10 CH.sub.2 : groups.
Quite recently, in U.S. Ser. No. 726,601, filed Jul. 8, 1991, which is incorporated herein by reference, thermotropic liquid crystal segmented block copolymers containing mesogenic and flexible coil polymer blocks have been described in which the rod blocks can be the type of liquid crystal polymer moieties described in the Ober et al. publication with the flexible coil moieties being polyester, for example. The synthesis procedure for making the block copolymers, in preferred embodiments, was a two-step reaction. In the first step, a hydroxyl-terminated aromatic mesogenic oligomer was synthesized from terephthaloyl chloride and the desired 1,4-bis(p-hydroxybenzoyloxy) alkane in one reactor and acid chloride-terminated polyester oligomers from terephthaloyl chloride and bis(4-hydroxyalkyl) terephthalate were synthesized in another reactor. In the second step both functionalized oligomers were combined to form the desired block copolymer. This procedure is more complicated than desired since it requires a transfer of one or both of the oligomers to complete the polymerization.
In U.S. Serial No. 779,477, filed Oct. 18, 1991, a single reactor process for formation of block copolymers comprising aromatic ester mesogenic units containing flexible polymethylene spacers and polyester flexible coil units in the main chain thereof was proposed which comprises:
(a) reacting an .alpha.,.omega.-bis(hydroxybenzoyloxy) alkane monomer with an aromatic acid chloride in a reactor to form a functionalized liquid crystal oligomer containing such mesogenic units; and PA1 (b) thereafter reacting the oligomer from (a) in the same reactor with either a subsequently added (i) polyester oligomer; or (ii) the reagents for synthesizing the polyester oligomer (i).
This process constituted an improvement over the type of process theretofore known for making the block coploymer.